On July 30th, 1975, former Teamsters union president Jimmy Hoffa disappeared in suburban Detroit -- although presumed dead, his remains have never been found.
On this date:
In 1729, the city of Baltimore was founded.

In 1792, the French national anthem "La Marseillaise", by Claude Joseph Rouget de Lisle, was first sung in Paris.

In 1844, the New York Yacht Club was founded.

In 1864, during the Civil War, Union forces tried to take Petersburg, Virginia, by exploding a mine under Confederate defense lines -- the attack failed.

In 1932, the Summer Olympic Games opened in Los Angeles.

In 1942, President Roosevelt signed a bill creating a women's auxiliary agency in the Navy known as "Women Accepted for Volunteer Emergency Service" -- WAVES for short.

In 1945, during World War Two, the USS "Indianapolis" was torpedoed by a Japanese submarine; only 316 out of 1,196 men survived the sinking and shark-infested waters.

In 1965, President Johnson signed into law the Medicare bill, which went into effect the following year.

In 1975, representatives of 35 countries convened in Finland for a conference on security and human rights that resulted in the Helsinki accords.

In 1980, the Israeli Knesset passed a law reaffirming all of Jerusalem as the capital of the Jewish state.

Ten years ago: British Conservative Party lawmaker Ian Gow was killed in a bombing claimed by the Irish Republican Army.

Five years ago: Russia and Chechen rebels signed an agreement calling for a gradual withdrawal of Russian troops and the disarmament of rebel fighters.

One year ago: Republicans pushed their $792 billion-dollar tax cut through the Senate. Linda Tripp, whose secretly recorded phone conversations with Monica Lewinsky led to the impeachment of President Clinton, was charged in Maryland with illegal wiretapping (prosecutors later dropped the charges). The leaders of some 40 nations gathered in Sarajevo, Bosnia-Herzegovina, pledging to push economic and democratic reforms for the war-torn Balkans.